U.S. Pat. Nos. 34170, 36292, 206671, and 884215 are illustrative of prior art machines for moving a workpiece past a workpiece treating means. Each of the prior art mechanisms include a fixture adapted to support the workpiece; means mounting the fixture for universal movement in a prescribed plane, a workpiece treating means so located as to treat a part of the workpiece proximate to the workpiece periphery as the workpiece part moves past the workpiece treating means; and drive means effective to so move the fixture in the prescribed plane as to move successive segments of the workpiece part past the workpiece treating means.
U.S. Pat. Nos. 34170 and 884215 disclose an adjustable track mounted to the fixture that so coacts with the drive means that the extent of lengthwise movements of the fixture to move lengthwise portions of the workpiece part past the workpiece treating means may be varied by adjusting the lengthwise dimension of the track in accordance with the lengthwise dimension of the workpiece. In accordance with a first aspect of this invention, these prior art mechanisms are improved so as to provide locating members that are adjustable so as to be spaced from each other an amount that is related to the lengthwise adjustment of the track to thereby enable the workpiece to be automatically positioned on the fixture in a position appropriate to the length of the workpiece and to the extent of lengthwise movements of the workpiece past the workpiece treating means. This is accomplished by making the adjustable track in the form of a pair of track sections having facing concave end portions and overlapping finger portions that extend from opposite ends of the concave end portions, as in U.S. Pat. No. 34170, and in providing a locating plate that is mounted to each concave track portion and that extends upwardly of the fixture.
A second aspect of the invention deals with an improved drive means that is cooperative with the track to move the fixture as described above regardless of the lengthwise adjustment of the track. This is accomplished by making the overlapping finger portions offset from each other and by making the drive means in the form of rollers engagable with opposite sides of the track sections.
A third aspect of the invention deals with an improved arrangement for clamping the workpiece to the fixture in flattened condition. The machine, in accordance with this aspect of the invention, includes a hold-down bar, having a flat bottom and a prescribed length, that is adapted to bear against the top of the workpiece. The fixture has a plurality of plungers mounted thereto for heightwise movement that are located side by side beneath the hold-down bar and have an overall length corresponding to the prescribed length of the hold-down bar. Means are provided for initially maintaining the plungers in lower positions and for then yieldably urging the plungers upwardly to thereby press the workpiece against the flat bottom of the hold-down bar and thus flatten the workpiece against the hold-down bar. The hold-down bar is mounted for universal movement in a plane parallel to the plane of movement of the fixture.
A fourth aspect of the invention is concerned with an improved arrangement for mounting the fixture for universal movement in the prescribed plane in such a way as to properly balance the fixture during this movement. This arrangement comprises a link to which the fixture is mounted for rotary movement about a heightwise axis that intersects the fixture proximate to its center of mass and that is at right angles to the plane of movement of the fixture, and linkage swingably connecting the link to a fixed structure.